Research on the psychology of simple, perceptual choices has led to an impressive progress in capturing the underlying mental processes as optimal mechanisms. Within this theoretical framework, perceptual decisions arise from a feed-forward process involving the sampling and accumulation of momentary evidence up to a decision boundary. According to this view, the stage where the information is accumulated is automatic and decision makers can exert strategic control on the decision boundary only, in order to adapt their performance to the task demands (e.g. speed-accuracy trade-offs). We present new behavioural and eye-tracking data challenging this view and suggesting that the way information is accumulated in perceptual decisions, is subject to differential weighing that depends on the task framing (e.g. select the brightest or the darkest spot). We conclude that choices are mostly influenced by extreme values, and whether positive or negative peaks are more pivotal is frame-dependent and subject to top-down control.